Accelerator for curing resins

ABSTRACT

Accelerator solution suitable for forming a redox system with peroxides, comprising (i) a compound of a first transition metal selected from manganese and copper, (ii) a compound of a second transition metal; the weight ratio of first transition metal:second transition metal being in the range 3:1 to 200:1, (iii) a nitrogen-containing base, and (iv) a hydroxy-functional solvent, with the proviso that the accelerator solution does not contain ascorbic acid.

The present invention relates to an accelerator solution suitable forforming a redox system with peroxides, a pre-accelerated resincomposition comprising an unsaturated polyester resin or vinyl esterresin, and a two-component composition comprising said pre-acceleratedresin composition.

Redox systems can be applied for resin curing. Conventional redoxsystems comprise an oxidizing agent (e.g. a peroxide) and a solubletransition metal ion as accelerator. The accelerator serves to increasethe activity of the oxidizing agent at lower temperatures and,consequently, to speed up the curing rate.

Accelerator systems can be added to the resin to be cured in differentways. One method involves the addition of the individual acceleratoringredients to the resin, before the peroxide is added. This can be donejust in advance of peroxide addition or days or weeks before that. Inthe latter case, we refer to a pre-accelerated resin composition, whichcomprises the resin and the accelerator ingredients and can be storeduntil further use and cure with the peroxide. Another method involvesthe pre-preparation of an accelerator solution containing theaccelerator ingredients, which solution can be stored until further useand addition to the resin. A pre-accelerated resin can be prepared byeither adding the individual ingredients of the accelerator system tothe resin or by adding these ingredients in admixture in the form of anaccelerator solution.

Typical accelerator systems comprise a transition metal salt or complex.The most frequently used transition metal for this purpose is cobalt.However, legislation requires reduction of the amount of cobalt in viewits toxicity.

As a result, there is a desire for the provision of Co-freeaccelerators. However, the Co-free accelerator systems that have beendeveloped up to now do not have the good performance of the traditionalCo-containing ones.

Examples of documents disclosing such Co-free accelerator systems are WO2008/003492, WO 2008/003793, and WO 2008/003500. The metals used in theaccelerator systems according to these documents—instead of Co—are Mn,Cu, Fe, and Ti. The disclosed accelerator systems are present in anunsaturated polyester or vinyl ester resin in the form of apre-accelerated resin. This pre-accelerated resin is said to containless than 0.01 mmol Co per kg resin.

It has now been found that the reactivity of accelerator systems basedon transition metals other than Co—e.g. Mn and Cu—can be enhanced by theaddition of a reactivity booster. This reactivity booster is atransition metal salt or complex which is present in the acceleratorsystem in a small amount compared to the primary transition metal (e.g.Mn or Cu).

The invention therefore relates to an accelerator solution suitable forforming a redox system with peroxides, comprising

-   -   (i) a compound of a first transition metal selected from        manganese and copper,    -   (ii) a compound of a second transition metal; the weight ratio        of first transition metal:second transition metal being in the        range 3:1 to 200:1,    -   (iii) a nitrogen-containing base, and    -   (iv) a hydroxy-functional solvent,        with the proviso that the accelerator solution does not contain        ascorbic acid.

The invention also relates to a pre-accelerated resin compositioncomprising

-   -   (i) a curable resin,    -   (ii) a compound of a first transition metal selected from        manganese and copper,    -   (iii) a compound of a second transition metal; the weight ratio        of first transition metal:second transition metal being in the        range 3:1 to 200:1,    -   (iv) a nitrogen-containing base, and    -   (v) a hydroxy-functional solvent,        with the proviso that the pre-accelerated resin does not contain        ascorbic acid.

The invention further relates to a two-component composition comprisinga first component and a second component, the first component comprisingthe pre-accelerated resin composition as defined above, the secondcomponent comprising a peroxide.

The first transition metal is selected from copper, and manganese.

The first transition metal is preferably present in the acceleratorsolution, determined as metal, in an amount of at least 50 mmol/l, morepreferably at least 100 mmol/l. It is preferably present in theaccelerator solution in an amount of less than 5000 mmol/l, morepreferably less than 2500 mmol/l, and most preferably less than 1000mmol/l.

The first transition metal is preferably present in a pre-acceleratedresin, determined as metal, in an amount of at least 1 mmol/kg resin,more preferably at least 2 mmol/kg resin. It is preferably present in anamount of not more than 75 mmol/kg resin, more preferably not more than50 mmol/kg resin, even more preferably not more than 25 mmol/kg resin,and most preferably not more than 10 mmol/kg resin.

Examples of the second transition metals, i.e. the reactivity boosters,are transition metals that can exist in two oxidation states, such ascobalt, titanium, vanadium, iron, manganese, copper, tin, chromium,nickel, molybdenum, germanium, strontium, palladium, platinum, niobium,antimony, rhenium, osmium, iridium, platinum, gold, mercury, tellurium,rubidium, and bismuth.

Preferred second transition metals as reactivity boosters according tothe present invention are copper, cobalt, titanium, iron, and manganese.Even more preferred are cobalt, titanium, iron, and manganese. Mostpreferred are cobalt and titanium.Cobalt compounds can be used as secondtransition metal (reactivity booster) without resulting in legislativeand toxicity problems because of the small amounts that can be used.

The second transition metal is preferably present in the acceleratorsolution, determined as metal, in an amount of at least 10 mmol/l, morepreferably at least 25 mmol/l. It is preferably present in theaccelerator solution in an amount of less than 1000 mmol/l, morepreferably less than 500 mmol/l, and most preferably less than 250mmol/l.

The second transition metal is preferably present in a pre-acceleratedresin, determined as metal, in an amount of at least 0.02 mmol/kg resin,more preferably at least 0.10 mmol/kg resin, even more preferably atleast 0.25 mmol/kg resin, and most preferably 0.50 mmol/kg resin. It ispreferably present in an amount of not more than 10 mmol/kg resin, morepreferably not more than 5 mmol/kg resin, and most preferably not morethan 2 mmol/kg resin.

It should be clear that the first and the second transition metals in aparticular solution or resin should differ from each other. In otherwords, the solution or resin should contain at least two differentmetals.

Suitable compounds of the first and second transition metals are saltsand complexes thereof, such as their halides, nitrate, sulphate,sulphonate, phosphate, phosphonate, oxide, or carboxylates. Examples ofsuitable carboxylates are lactate, 2-ethyl hexanoate, acetate,proprionate, butyrate, oxalate, laurate, oleate, linoleate, palmitate,stearate, acetyl acetonate, octanoate, nonanoate, heptanoate,neodecanoate, or naphthenate.

Preferred manganese compounds are manganese chloride, nitrate, sulphate,lactate, 2-ethyl hexanoate, octanoate, nonanoate, heptanoate,neodecanoate, naphthenate, and acetate and the Mn complexes of pyridine,bipyridine and derivatives thereof, and of the tridentate, tetradentate,pentadentate, or hexadentate nitrogen donor ligands disclosed in WO2011/83309.

Preferred nitrogen donor ligands according to WO 2011/83309 are thebispidon ligands and the TACN-Nx ligands. The preferred bispidon ligandisdimethyl-2,4-di-(2-pyridyl)-3-methyl-7-(pyridin-2-ylmethyl)-3,7-diaza-bicyclo[3.3.1]nonan-9-one-1,5-dicarboxylate(N2py3o-Cl). The preferred TACN-Nx ligand is1,4,7-trimethyl-1,4,7-triazacyclononane (Me₃-TACN).

Any one of Mn(II), Mn(III), Mn(IV) and Mn(VII) compounds can be used.

Preferred copper compounds are copper chloride, nitrate, sulphate,lactate, 2-ethyl hexanoate, octanoate, nonanoate, heptanoate,neodecanoate, naphthenate, and acetate. Both Cu(I) and Cu(II) compoundscan be used.

Suitable nitrogen-containing bases to be present in the acceleratorsolution and the pre-accelerated resin are tertiary amines such astriethyl amine, dimethylaniline, diethylaniline, orN,N-dimethyl-p-toludine (DMPT), polyamines such as 1,2-(dimethylamine)ethane, secondary amines such as diethyl amine, ethoxylated aminessuch as triethanol amine, dimethylamino ethanol, diethanol amine, ormonoethanol amine, and aromatic amines such as bipyridine.

The nitrogen-containing base is preferably present in the acceleratorsolution in an amount of 5-50 wt %. In the pre-accelerator resin it ispreferably present in an amount of 0.5-10 g/kg resin.

The term “hydroxy-functional solvent” includes compounds of the formulaHO—(—CH₂—C(R¹)₂—(CH₂)_(m)—O—)_(n)—R², wherein each R¹ is independentlyselected from the group consisting of hydrogen, alkyl groups with 1-10carbon atoms, and hydroxyalkyl groups with 1 to 10 carbon atoms, n=1-10,m=0 or 1, and R² is hydrogen or an alkyl group with 1-10 carbon atoms.Most preferably, each R¹ is independently selected from H, CH₃, andCH₂OH. Examples of suitable hydroxy-functional solvents are glycols likediethylene monobutyl ether, ethylene glycol, diethylene glycol,dipropylene glycol, and polyethylene glycols, glycerol, andpentaerythritol.

The hydroxy-functional solvent is preferably present in the acceleratorsolution in an amount of 1-50 wt %, preferably 5-30 wt %. In thepre-accelerator resin it is preferably present in an amount of 0.1-100g/kg resin, preferably 0.5-60 g/kg resin.

The accelerator solution and the pre-accelerated resin according to thepresent invention do not contain ascorbic acid, because ascorbic acidtends to counteract the effect of the reactivity booster. In thepresence of ascorbic acid, the second metal may act as an inhibitorinstead of a reactivity booster.

Within this specification, the term ascorbic acid includes L-ascorbicacid and D-isoascorbic acid.

The accelerator solution and the pre-accelerated resin according to thepresent invention may optionally contain one or more promoters, water,additives, and/or fillers.

There are three important classes of promoters: metal carboxylate salts,1,3-diketones, and phosphorous-containing compounds.

Examples of 1,3-diketones are acetyl acetone, benzoyl acetone, anddibenzoyl methane, and acetoacetates such as diethyl acetoacetamide,dimethyl acetoacetamide, dipropylacetoacetamide, dibutylacetoacetamide,methyl acetoacetate, ethyl acetoacetate, propyl acetoacetate, andbutylacetoacetate.

Examples of suitable metal carboxylate salts are the 2-ethyl hexanoates,octanoates, nonanoates, heptanoates, neodecanoates, and naphthenates ofammonium, alkali metals, and alkaline earth metals. A preferred alkalimetal is K.

The salts may be added to the accelerator solution or the resin as such,or they may be formed in situ. For example, alkali metal 2-ethylhexanoates can be prepared in situ in the accelerator solution, afteraddition of the alkali metal hydroxide and 2-ethyl hexanoic acid to thesolution.

Examples of phorphorous-containing compounds are phosphorous compoundswith the formulae P(R)₃ and P(R)₃=0, wherein each R is independentlyselected from hydrogen, alkyl with 1 to 10 carbon atoms, and alkoxygroups with 1 to 10 carbon atoms. Preferably, at least two R-groups areselected from either alkyl groups of alkoxy groups. Specific examples ofsuitable phosphorous-containing compounds are diethyl phosphate, dibutylphosphate, tributyl phosphate, triethyl phosphate (TEP), dibutylphosphite, and triethyl phosphate.

Acetoacetates are particularly preferred promoters. Particularlypreferred is diethyl acetoacetamide. Even more preferred is acombination of diethyl acetoacetamide and potassium 2-ethyl hexanoate.Also preferred is a combination of diethyl acetoacetamide and dibutylphosphate.

If one or more promoters is/are present in the accelerator solution,their amount preferably is at least 0.01 wt %, more preferably at least0.1 wt %, even more preferably at least 1 wt %, more preferably at least10 wt %, and most preferably at least 20 wt %; preferably not more than90 wt %, more preferably not more than 80 wt %, and most preferably notmore than 70 wt %, all based on the total weight of the acceleratorsolution.

The accelerator solution according to the present invention may furthercomprise additional organic compounds, such as aliphatic hydrocarbonsolvents, aromatic hydrocarbon solvents, and solvents that carry analdehyde, ketone, ether, ester, alcohol, phosphate, or carboxylic acidgroup. Examples of suitable solvents are aliphatic hydrocarbon solventssuch as white spirit and odourless mineral spirit (OMS), aromatichydrocarbon solvents such naphthenes and mixtures of naphthenes andparaffins, isobutanol; pentanol; 1,2-dioximes, N-methyl pyrrolidinone,N-ethyl pyrrolidinone; dimethyl formamide (DMF); dimethylsulfoxide(DMSO); 2,2,4-trimethylpentanediol diisobutyrate (TxIB); esters such asdibutyl maleate, dibutyl succinate, ethyl acetate, butyl acetate, mono-and diesters of ketoglutaric acid, pyruvates, and esters of ascorbicacid such as ascorbic palmitate; aldehydes; mono- and diesters, more inparticular diethyl malonate and succinates; 1,2-diketones, in particulardiacetyl and glyoxal; benzyl alcohol, and fatty alcohols.

The accelerator solution may optionally comprise water. If present, thewater content of the solution preferably is at least 0.01 wt % and morepreferably at least 0.1 wt %. The water content is preferably not morethan 50 wt %, more preferably not more than 40 wt %, more preferably notmore than 20 wt %, even more preferably not more than 10 wt %, and mostpreferably not more than 5 wt %, all based on the total weight of theaccelerator solution.

The accelerator solution can be prepared by simply mixing theingredients, optionally with intermediate heating and/or mixing steps.

The pre-accelerated resin can be prepared in various ways: by mixing theindividual ingredients with the resin, or by mixing the resin, includingoptional monomer, with the accelerator solution according to the presentinvention. The latter method is preferred.

Suitable resins to be cured using the accelerator solution according tothe invention and to be present in the pre-accelerated resin compositioninclude alkyd resins, unsaturated polyester (UP) resins, vinyl esterresins, (meth)acrylate resins, polyurethanes, epoxy resins, and mixturesthereof. Preferred resins are (meth)acrylate resins, UP resins and vinylester resins. In the context of the present application, the terms“unsaturated polyester resin” and “UP resin” refer to the combination ofunsaturated polyester resin and ethylenically unsaturated monomericcompound. The term “(meth)acrylate resin” refers to the combination ofacrylate or methacrylate resin and ethylenically unsaturated monomericcompound. UP resins and acrylate resins as defined above are commonpractice and commercially available. Curing is generally started byeither adding the accelerator solution according to the invention andthe initiator (peroxide) to the resin, or by adding the peroxide to thepre-accelerated resin.

Suitable UP resins to be cured by the process of the present inventionare so-called ortho-resins, iso-resins, iso-npg resins, anddicyclopentadiene (DCPD) resins. Examples of such resins are maleic,fumaric, allylic, vinylic, and epoxy-type resins, bisphenol A resins,terephthalic resins, and hybrid resins.

Vinyl ester resins include acrylate resins, based on, e.g. methacrylate,diacrylate, dimethacrylate, and oligomers thereof.

Acrylate resins include acrylates, methacrylates, diacrylates anddimethacrylates, and oligomers thereof.

Examples of ethylenically unsaturated monomeric compounds includestyrene and styrene derivatives like a-methyl styrene, vinyl toluene,indene, divinyl benzene, vinyl pyrrolidone, vinyl siloxane, vinylcaprolactam, stilbene, but also diallyl phthalate, dibenzylideneacetone, allyl benzene, methyl methacrylate, methylacrylate,(meth)acrylic acid, diacrylates, dimethacrylates, acrylamides; vinylacetate, triallyl cyanurate, triallyl isocyanurate, allyl compoundswhich are used for optical application (such as (di)ethylene glycoldiallyl carbonate), chlorostyrene, tert-butyl styrene,tert-butylacrylate, butanediol dimethacrylate and mixtures thereof.Suitable examples of (meth)acrylates reactive diluents are PEG200di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,3-butanedioldi(meth)acrylate, 2,3-butanedioldi(meth)acrylate, 1,6-hexanedioldi(meth)acrylate and its isomers, diethyleneglycol di(meth)acrylate,triethyleneglycol di(meth)acrylate, glycerol di(meth)acrylate,trimethylolpropane di(meth)acrylate, neopentyl glycol di(meth)acrylate,dipropyleneglycol di(meth)acrylate, tripropyleneglycol di(meth)acrylate,PPG250 di(meth)acrylate, tricyclodecane dimethylol di(meth)acrylate,1,10-decanediol di(meth)acrylate, tetraethylene glycol di(meth)acrylate,trimethylolpropanetri(meth)acrylate, glycidyl (meth)acrylate,(bis)maleimides, (bis)citraconimides, (bis)itaconimides, and mixturesthereof. The amount of ethylenically unsaturated monomer in thepre-accelerated resin is preferably at least 0.1 wt %, based on theweight of the resin, more preferably at least 1 wt %, and mostpreferably at least 5 wt %. The amount of ethylenically unsaturatedmonomer is preferably not more than 50 wt %, more preferably not morethan 40 wt %, and most preferably not more than 35 wt %.

If an accelerator solution is used for curing a resin or for preparing apre-accelerated resin, the accelerator solution is generally employed inamounts of at least 0.01 wt %, preferably at least 0.1 wt %, andpreferably not more than 5 wt %, more preferably not more than 3 wt % ofthe accelerator solution, based on the weight of the resin.

Peroxides suitable for curing the resin and suitable for being presentin the second component of the two-component composition includeinorganic peroxides and organic peroxides, such as conventionally usedketone peroxides, peroxyesters, diaryl peroxides, dialkyl peroxides, andperoxydicarbonates, but also peroxycarbonates, peroxyketals,hydroperoxides, diacyl peroxides, and hydrogen peroxide. Preferredperoxides are organic hydroperoxides, ketone peroxides, peroxyesters,and peroxycarbonates. Even more preferred are hydroperoxides and ketoneperoxides. Preferred hydroperoxides include cumyl hydroperoxide,1,1,3,3-tetramethylbutyl hydroperoxide, tert-butyl hydroperoxide,isopropylcumyl hydroperoxide, tert-amyl hydroperoxide,2,5-dimethylhexyl-2,5-dihydroperoxide, pinane hydroperoxide,para-menthane-hydroperoxide, terpene-hydroperoxide and pinenehydroperoxide. Preferred ketone peroxides include methyl ethyl ketoneperoxide, methyl isopropyl ketone peroxide, methyl isobutyl ketoneperoxide, cyclohexanone peroxide, and acetylacetone peroxide.

Of course, also mixtures of two or more peroxides can be used; forinstance a combination of a hydroperoxide or ketone peroxide with aperoxyester.

A particularly preferred peroxide is methyl ethyl ketone peroxide. Theskilled person will understand that these peroxides can be combined withconventional additives, for instance fillers, piments, andphlegmatisers. Examples phlegmatizers are hydrophilic esters andhydrocarbon solvents. The amount of peroxide to be used for curing theresin is preferably at least 0.1 per hundred resin (phr), morepreferably at least 0.5 phr, and most preferably at least 1 phr. Theamount of peroxide is preferably not more than 8 phr, more preferablynot more than 5 phr, most preferably not more than 2 phr.

When the peroxide is mixed with the pre-accelerated resin, is added to apre-mix of resin and accelerator solution, or is pre-mixed with theresin after which accelerator solution is added. The resulting mixtureis mixed and dispersed. The curing process can be carried out at anytemperature from −15° C. up to 250° C., depending on the initiatorsystem, the accelerator system, the compounds to adapt the curing rate,and the resin composition to be cured. Preferably, it is carried out atambient temperatures commonly used in applications such as hand lay-up,spray-up, filament winding, resin transfer moulding, coating (e.g.gelcoat and standard coatings), button production, centrifugal casting,corrugated sheets or flat panels, relining systems, kitchen sinks viapouring compounds, etc. However, it can also be used in SMC, BMC,pultrusion techniques, and the like, for which temperatures up to 180°C., more preferably up to 150° C., most preferably up to 100° C., areused.

Other optional additives may be employed in the curing process accordingto the invention, such as fillers, glass fibres, pigments, inhibitors,and promoters.

The cured resins find use in various applications, including marineapplications, chemical anchoring, roofing, construction, relining, pipesand tanks, flooring, windmill blades, etc.

EXAMPLES Example 1

Two Cu-containing accelerator solutions were prepared, the differencebeing a small amount of Co. The Co was added by adding 0.045wt % (basedon the weight of the accelerator solution) of the commercially availableAccelerator NL-53 (ex-AkzoNobel), comprising cobalt (II)2-ethylhexanoate in an amount of 10 wt % Co (as metal),

The ingredients of the solutions are listed in Table 1.

These accelerator solutions—0.5 phr (per hundred resin)—were used tocure an ortho phthalic acid-based unsaturated polyester resin (Palatal®P6 ex DSM resin) at 20° C. with 1.5 phr methyl ethyl ketone peroxide(Butanox® M50, ex-AkzoNobel). The curing performance was analysed by themethod of the Society of Plastic Institute (SPI method F/77.1; availablefrom Akzo Nobel Polymer Chemicals). This method involves measuring thepeak exotherm, the time to peak, and the gel time. According to thismethod, 25 g of a mixture comprising 100 parts of resin, 1.5 parts ofperoxide, and 0.5 parts of accelerator solution were poured into a testtube and a thermocouple was placed through the enclosure at the centreof the tube. The glass tube was then placed in a climate controlled roommaintained at 20° C. and the time-temperature curve was measured. Fromthe curve the following parameters were calculated:

Gel time (Gt)=time in minutes elapsed between the start of theexperiment and 5.6° C. above the bath temperature.

Time to peak (TTP)=time elapsed between the start of the experiment andthe moment that the peak temperature is reached.

Peak exotherm (PE)=the maximum temperature that is reached.

The results are displayed in Table 1, which also includes a referenceexperiment using only Accelerator NL-53 (0.045 phr).

TABLE 1 Comp. exp. 1 Comp. exp. 2 Exp. 3 Diethylene glycol (wt %) — 2019.95 Diethanol amine (wt %) — 25 25 Diethyl acetoacetamide — 40 40 (wt%) Dibutyl phosphate (wt %) — 10 10 Cu(I) chloride (wt %) — 5 5Accelerator NL-53 (wt %) 100 — 0.045 Gt (min) 18 21 3 TTP (min) 32 42 8PE (° C.) 152.3 153.4 151.9

Example 2

Example 1 was repeated with two other Cu-containing acceleratorsolutions. The results are displayed in Table 2.

TABLE 2 Comp. exp. 1 Comp. exp. 2 Exp. 3 Diethylene glycol (wt %) — 5 5Diethanol amine (wt %) — 25 25 Diethyl acetoacetamide — 45 45 (wt %) Koctanoate (wt %) — 20 20 Cu(II) acetate (wt %) — 5 5 Accelerator NL-53(wt %) 100 — 0.045 Gt (min) 18 26 4 TTP (min) 32 38 7 PE (° C.) 152.3163.7 175.4

1. Accelerator solution suitable for forming a redox system withperoxides, comprising (i) a compound of a first transition metalselected from manganese and copper, (ii) a compound of a secondtransition metal; the weight ratio of first transition metal:secondtransition metal being in the range 3:1 to 200:1, (iii) anitrogen-containing base, and (iv) a hydroxy-functional solvent, withthe proviso that the accelerator solution does not contain ascorbicacid.
 2. Accelerator solution according to claim 1 wherein the secondtransition metal is selected from the group consisting of Co, Ti, Fe,Mn, Cu, Sn, Cr, Ni, Mo, Ge, Sr, Pd, Pt, Nb, Sb, Re, Os, Ir, Pt, Au, Hg,Te, Rb, and Bi.
 3. Accelerator solution according to claim 2 wherein thesecond transition metal is selected from the group consisting of Co, Ti,Fe, Mn, and Cu.
 4. Accelerator solution according to claim 1 wherein thefirst transition metal is present in the solution in an amount of50-5000 mmol/l.
 5. Accelerator solution according to claim 1 wherein thesecond transition metal is present in the solution in an amount of10-1000 mmol/l.
 6. Accelerator solution according to claim 1 furthercomprising an alkali or alkaline earth metal compound, a phosphorous-containing compound, and/or a 1,3-diketone.
 7. Pre-accelerated resincomposition comprising (i) a curable resin, (ii) a compound of a firsttransition metal selected from manganese and copper, (iii) a compound ofa second transition metal; the weight ratio of first transitionmetal:second transition metal being in the range 3:1 to 200:1 (iv) anitrogen-containing base, and (v) a hydroxy-functional solvent with theproviso that the pre-accelerated resin does not contain ascorbic acid.8. Pre-accelerated resin composition according to claim 7 wherein thesecond transition metal is selected from the group consisting of Co, V,Ti, Fe, Mn, Cu, Sn, Cr, Ni, Mo, Ge, Sr, Pd, Pt, Nb, Sb, Re, Os, Ir, Pt,Au, Hg, Te, Rb, and Bi.
 9. Pre-accelerated resin composition accordingto claim 8 wherein the second transition metal is selected from thegroup consisting of Co, V, Ti, Fe, Mn, and Cu.
 10. Pre-accelerated resincomposition according to claim 7 wherein the first transition metal ispresent in the solution in an amount of 1-75 mmol/kg resin. 11.Pre-accelerated resin composition according to claim 7 wherein thesecond transition metal is present in the solution in an amount of0.10-10 mmol/kg resin.
 12. Pre-accelerated resin composition accordingto claim 7 further comprising an alkali or alkaline earth metalcompound, a phosphorous-containing compound, and/or a 1,3-diketone. 13.Pre-accelerated resin composition according to claim 7 wherein thecurable resin is an unsaturated polyester resin, a vinyl ester resin, ora (meth)acrylate resin.
 14. Two-component composition comprising a firstcomponent and a second component, the first component comprising thepre-accelerated resin composition according to claim 7, the secondcomponent comprising a peroxide.
 15. Two component composition accordingto claim 14 wherein the peroxide is selected from the group consistingof organic hydroperoxides, ketone peroxides, peroxycarbonates, andperoxyesters.